Pros
Lot of learning opportunities. Very intelligent co-workers. The scale of problems are so big, only few companies have problems at such large scale.
Kontras
Not a startup and they keep saying frugality drives innovation but we do not need to be frugal any more so generally we get away by adding a few hundred machines every time a scale issue comes up. Management forces SDE-II/SDE-III to be influential but that creates a bad work environment. Senior engineers have to force their decisions on junior engineers to meet their goals. Works well until you are SDE-I but as you become more experienced you would probably like to understand why trade-offs you are making in your design/development are worst then suggested by some other senior engineer.